1. Technical Field
The present invention relates to a method of preparing a catalyst using alkali metal and/or alkaline earth metal components inherently contained in natural cellulose fibers as a dispersant and a co-catalyst of catalytic metal particles, and more particularly, to a method of preparing a catalyst using alkali metal and alkaline earth metal components such as Ca, Mg, K, etc., which are inherently contained in the structure of natural cellulose fibers, as a dispersant and a performance improver.
2. Description of the Related Art
Recently, in the main research trends of catalyst fields, a first interesting development is the preparation of a support that is physically and chemically stable and has a large surface area with a uniform pore distribution adapted for a specific reaction, and a second interesting development is the preparation of a catalyst that exhibits the greatest activity at the lowest cost by supporting catalyst particles in a state of being highly dispersed while being minimized to a nanoscale.
Particularly in the case where a metal nanocatalyst is applied to a high-temperature catalytic reaction, most metal particles may agglomerate. Even when the dispersibility of catalyst particles that were first prepared is very high, the catalyst rapidly agglomerates and becomes undesirably deactivated at the same time when being exposed to the high-temperature reaction.
As the price of precious metal catalysts has increased considerably in recent years, catalysts for fuel cells and for H2 preparation using precious metal catalysts such as Au and Pt are problematic in terms of being deactivated because of the agglomeration of metal. With the goal of overcoming such problems, a variety of attempts are being made to disperse a metal having no reaction activity in order to impart steric hindrance between metal particles, or to strengthen the interactions between the metal and the support to thereby prevent the transfer and agglomeration of the catalyst upon high-temperature catalytic reaction. However, satisfactory research results have not yet been reported to date.
Vizcaino et al. (Catalysis Today 146 (2009) 63-70) prepared a catalyst that is effective in a water vapor reforming reaction of ethanol by adding Mg and Ca to a Cu—Ni/SBA-15 catalyst. They also reported that the added Ca and Mg components improve the dispersibility of a CuNi catalyst, enhance the interaction between the support and the metal catalyst to increase catalytic performance, and lower the deactivation due to coke formation. Research results regarding improvements in catalytic performance and durability owing to the addition of alkaline earth metals were published in many reports in addition to the above paper (Cortright et al., Nature 418 (2002) 964; Pol el al. Carbon 42 (2004)111). However, methods of artificially adding an alkali metal and an alkaline earth metal to a catalyst for a reforming reaction have been studied. Research results for techniques for utilizing components such as, for example, Ca and Mg inherently contained in natural cellulose fibers have not yet been published.
Therefore, the present inventors continued research into preparation of catalysts having improved catalytic performance and durability without performing the artificial addition of alkali metal and alkaline earth metal components, leading to the development of a method of using highly dispersed alkali metal and alkaline earth metal nanoparticles that are inherently present in the structure of natural cellulose fibers as a dispersant and a performance improver.